Some Aspects Of The Biology Of Chrysichthys nigrodigitatus (Pisces:Siluroidae) In Asa Lake Ilorin, Nigeria

Abstract

Investigation into reproductive biology and the food and feeding habit of the 240 specimens of catfish Chrysichthys nigrodigitatus from Asa Lake in Kwara State, Nigeria was made. The total length of Chrysichthys nigrodigitatus ranged from 12.20 – 19.80 cm. The total body weight ranged from 9.76 – 58.030 g. The male length ranged from 12.20 – 19.80 cm while the female length ranged from 13.40 – 19.50 cm. Their weight ranges include 9.76 – 58.03 and 10.01 – 56.61 g in male and female respectively. The mean condition factor of the fish was 0.95 for both male and female. Male has the mean condition factor of 1.12 while the female mean condition factor is 0.98. The sex ratio of male to female was 1:8:2.1. The number of specimen for the stages of the gonad development varied for all the stages. The mean gonado-somatic indices for male and female were 0.29 and 3.27 respectively. The food items discovered in the stomach of C. nigrodigitatus were plant materials, mollusks, insect and fries of the same fish. Others are protozoan, worm, detritus, ova, and sand grain. The feeding flexibility and the fish size with respect to breeding and feeding habit were discussed.

Keywords: Chrysichthys nigrodigitatus, reproduction, feeding habit, Asa lake

Nigerian Journal of Fisheries Vol. 5 (1) 2008: pp. 73-84